1. Field of the Invention
This invention is directed to fill control valves in general, and to a fill control valve which incorporates a check valve operation which is used to control a container filling operation, in particular.
2. Prior art
There are many types of fill valves, control valves and check valves known in the art. These valves are frequently used in various techniques employed in filling of containers or utensils which receive some type of liquid material. One notable usage is in the filling of containers with soft drinks. In the past, bottles have been used and particular kinds of valves have been required. In recent history, many soft drinks are now distributed in cans made of tin or aluminum, or the like. These cans are filled on large filling machines which can fill many cans concurrently while moving the cans in a substantially continuous path around or through the machine. Typically, the machine includes a large reservoir of the liquid to be placed in the containers and a large plurality of filling valves. In some types of known filling machines, it is typical to provide in the neighborhood of 40 to 130 filling valves which can fill up to 1850 cans per minute. Of course, the number of cans to be filled is a function of numerous parameters including the number of filling valves, the temperature of the liquid, the temperature of the environment wherein the filling takes place, and the type of liquid (for example whether it is carbonated or not).
Another problem which is encountered in filling soft drink containers is the fact that the carbonation in the liquid frequently causes bubbling or frothing of the liquid if it is fed into the can too rapidly. A "sniffer" line is, typically, used to remove this excess froth or foam. If the froth is of a substantial nature, it will sometimes, activate the check valve apparatus so that a "short fill" in the can or container occurs. Conversely, if the fill rate is slow, the entire operation is slowed. Therefore, this is not a really viable alternative process to avoid the problems associated with frothing of liquid.
Still another problem encountered in can filling machines is that the fluid (typically gaseous) in the container must be displaced and removed. A fill control valve is disposed on the filling machine apparatus to be adjacent the top of the container so that the displaced fluid (gas) can pass therethrough and escape. However, the fill control valve must also be adapted to close when the contents (liquid) of the container reaches a prescribed level. Otherwise, product can be lost (through a late closing valve) or a short-fill can be produced (by an early closing valve). Therefore, the fill control valve can become a very important component in a filling machine. This fill control valve can have a very dramatic economic impact on the operation of the filling machine apparatus.
Inasmuch as the soft drink bottling business is a substantial industry, there are, obviously, many filling machines which are available on the market. These machines, of course, use valves to control the filling of the containers. The valves are, in many cases, operable and effective to the extent that they are available. However, the known valves suffer from difficulties in "short fills" as a result of excess gas or "double dribbles" caused by improper feeding techniques. Therefore, it is necessary and desirable to improve the operation and throughput of the system. Consequently, improved fill control valves are highly desirable.